1. Field of the Invention
This application relates to a photoresist composition and a method of manufacturing a display substrate using the photoresist composition. More particularly, this application relates to a photoresist composition that may be used for a display device, and a method of manufacturing a display substrate using the photoresist composition.
2. Description of the Related Art
In general, a liquid crystal display (“LCD”) panel includes a display substrate, an opposing substrate facing the display substrate and a liquid crystal layer interposed between the display substrate and the opposing substrate. The display substrate includes a gate pattern, a semiconductor pattern, a source pattern and a pixel electrode, which are formed sequentially on a base substrate. The gate pattern, the semiconductor pattern, the source pattern and the pixel electrode may be formed by patterning thin-film layers by a photolithography process.
Two different layers that are patterned by using two masks through a conventional method may also be patterned by using a single mask. For example, photoresist patterns having different thicknesses are formed on a first thin-film layer and a second thin-film layer, which are in turn sequentially formed. Thereafter, the first and second thin-film layers are patterned by etching, using the photoresist pattern as a mask. After patterning the first thin-film layer, a portion of the photoresist pattern is removed to form a remaining pattern, and the second thin-film layer is patterned by using the remaining pattern as a mask. In this way, the number of masks required may be reduced, thereby reducing the cost associated with the expense of using multiple masks.
However, when the second thin-film layer is patterned using the remaining pattern as a mask, the remaining pattern can be damaged by the etchant used to pattern the second thin-film layer, or may undergo reflow and thus loss of resolution or pattern collapse. As a result, the second thin-film layer may be more highly etched when compared to the first thin-film layer so that the first thin-film layer has a shape which protrudes through the second thin-film layer. When the second thin-film layer is a source metal layer and the first thin-film layer is a silicon layer, the second thin-film layer which substantially serves as an electrode or a signal line may have a smaller size than the first thin-film layer. Thus, the ratio of the sizes of openings in a display substrate may be reduced.
Accordingly, a photoresist pattern needs to have a high heat resistance in order to form a fine photoresist pattern. Furthermore, it is required that no cracks are generated at the surface of the photoresist pattern at a low temperature or by a chemical material, and that the photoresist pattern be readily removed by a stripper. However, when heat resistance of a photoresist pattern is enhanced, the photoresist pattern may not be readily removed by a stripper. Furthermore, when the manufacturing (processing) temperature is reduced so as to remove a photoresist pattern easily, cracks may be generated. Thus, there increasing need to develop a photoresist composition capable of solving those problems.